Sedimentation analysis in liquid-liquid system applied to biodiesel production research. introducing mathematical models

Abstract

This work is focused on description of gravitation separation process of the ester phase from the glycerol phase for biodiesel production. Four mathematical models describing separation were created. Two independent methods were used for monitoring of separation: the first method is based on the determination of the time dependence of the actual amount of the glycerol phase on the bottom of a sedimenting vessel by digital camera records. The second one measures light absorption changes caused by the lowering of the glycerol phase during the sedimentation. The obtained data was curve fitted by developed mathematical models, which are (i) based on Stokes equation and proposed distribution function, (ii) based on analogy to reaction kinetics. The distribution function has several simplified presumptions, e.g., interactions are neglected, the function has one peak. The obtained model parameters (from the curve fitting) can be consequently used for the quantification and the prediction of sedimentation behaviour such as the sedimentation conditions, the size of settling devices and the evaluation of dependences on raw material quality.